Wireless communication systems are in widespread use in virtually all metropolitan areas of the world. In particular, communication systems using a geographic frequency reuse scheme, more commonly known as cellular communications systems, are the most popular. As a communication device moves from one serving cell to another, communication service hands off from one cell to the next in corresponding fashion.
One drawback with these communication systems is that communication service is sometimes lost or interrupted. Primarily this occurs when the signal from the serving cell is lost, and no other serving cells can be detected. There are a number of common scenarios where this occurs. One occurs when the communication device is camped on a serving cell, meaning no hand off to another cell is imminent, and the communication device enters an area that is shielded from serving cell's signal, such as in elevator, or upon entering a tunnel. Another scenario occurs when the communication device travels from an area covered by a serving cell into zone where there is no serving coverage, often referred to as a "dead zone."
The conventional method of restoring service involves scanning the serving cell frequency that was in use when the interruption occurred, and the frequencies of the neighbor cells of the serving cell in an attempt to locate a suitable carrier. This method is fine for minor interruptions, but it fails to account for situations where the communication device has moved to a new area during the interruption. Therefore, there is a need for a method of restoring communication service to a communication device that takes into consideration the possibility that the communication device may be in a new region when it becomes possible to restore communication service.